Flow Uniformity Optimization for Diesel Aftertreatment Systems

In 2007 emissions regulations for on-road light to heavy duty Diesel trucks will require the use of Diesel Particulate Filters (DPFs). The uniform distribution of soot on the DPF is critical for adequate long term performance of these DPFs. This is especially true when cordierite is used instead of silicon carbide for the DPF substrate, due to the reduced thermal conductivity and reduced peak temperature capability of cordierite. In addition to flow uniformity, an inverted flow pattern where more of the flow is forced radially outward on the substrate face could be beneficial to counteract thermal losses in the converter.

This paper describes a dispersion device that can improve flow geometry with a low backpressure penalty. Computational fluid dynamics (CFD) results and experimental data are presented for this device. Additionally, cone design options are explored, and CFD analysis results of the cone design are presented. A parametric study is also described showing the boundary conditions that have the highest impact on CFD results of flow uniformity. This research has shown that substantial improvements in flow uniformity for large diameter substrates can be made through cone optimization. Further improvements in flow distribution can be made with the use of a dispersion device with little to no backpressure penalty if the device is optimized.